The Objectives of the Biostatistics Core activities are: 1. To maintain and implement where necessary, a comprehensive, high quality system of data entry, data management, quality control, and data security strategies for each of the four Projects and Cores A and C. II. To create data analysis plans using Project results and the data from the DCCT/EDIC Research Group and the VA Cooperative Studies trial. These activities involve analyses that examine the association of baseline measures from both of these studies and the molecular parameters being measured within each of the 4 Projects and Core C. III. To create data analysis plans using Project results and the data from the DCCT/EDIC Research Group and the VA Cooperative Study. These activities involve analyses that examine the development of macrovascular disease endpoints within the two study cohorts together with molecular parameters being measured within each of the 4 Projects and Core C. IV. To facilitate the statistical analysis plans of each Project and assist the investigators in using the results from all analyses.